The present invention relates to compacting vehicles, and more particularly to systems for watering or wetting the drums of a compacting vehicle.
Compacting vehicles or compactors are known and basically include a frame and one or two drums connected with the frame, the single drum vehicles including a pair of wheels in place of a second drum. Double drum compactors are typically used to compact mats of paving material (e.g., asphalt) formed by a paver to construct roadways, airport runways, parking lots or the like. Basically, the compacting vehicle continuously rolls back and forth over portions of the material mat such that the weight of the vehicle, aided by impacts from vibratory mechanisms within the drums, is transferred through the drums to compact the mat to a desired density.
During such compaction operations, it is desirable to continuously apply or coat the outer surfaces of the drums with a xe2x80x9cwettingxe2x80x9d fluid, typically water or a water-based solution. Otherwise, paving material tends to adhere to the outer surface of the drum(s), creating rips or tears in the mat where adhered material is pulled from the mat, depressions in the mat where the adhered material is pressed against the mat upper surface and/or high spots on the mat when the material is subsequently forced back onto the mat from the drum surface. In general, the hotter the material or the more xe2x80x9cseverexe2x80x9d the ambient conditions, the greater the volume of water/fluid required to adequately coat the drum outer surface to prevent dry spots from forming by evaporation. Further, the faster the rolling speed of the compactor, the greater the volume of water necessary to ensure that the drum surface remains coated to avoid material adhesion.
Generally, compacting vehicles are provided with a watering or xe2x80x9cwettingxe2x80x9d system that typically includes a supply of fluid, such as a fluid/water tank, fluid lines or hoses connected with the tank and a pump to drive the fluid from the tank and through the hoses. Further, one or more nozzle devices, such as multi-ported sprayer bars, are typically located near the drum to distribute fluid across the drum outer surface. As the supply of water is carried on board the vehicle, the water capacity of the wetting system, both in terms of the total volume of fluid available in the tanks and the total time to completely empty the tanks, is an important limitation of a compacting vehicle. As the water or other fluid must be replenished when the fluid supply is emptied, the compaction operation must therefore be halted for the amount of time necessary to replenish the water/fluid supply.
Various methods have been employed in the past to conserve water usage. One known method of conserving water usage is to provide a control system to automatically start and stop the wetting system when the compacting vehicle is respectively started from rest or stopped during a compaction operation. Further, manual controls, such as a manually-operated rheostat, have been provided to enable a vehicle operator to adjust the flow rate from the pumps to adapt to varying conditions of the material mat and operational speeds. However, particularly with less experienced operators, the operators often tend to just set the pump flow rate to the maximum rate, thereby failing to conserve wetting fluid and defeating the purpose of providing such controls. In addition, excessive wetting fluid applied to the drums tends to run-off onto the material mat and cause premature cooling of certain mat sections. Subsequent compaction by the drums, especially when performed in combination with a higher level of drum vibratory mechanisms, may cause superficial or shallow surface cracks to form in the material mat, which may reduce the intended useful life of the mat.
Therefore, in view of the above-discussed limitations with known wetting systems, it would be desirable to provide a control system for a compactor watering or wetting system that more adequately conserves water or other wetting fluid and which prevents the occurrence of excessive wetting that may lead to fluid-runoff.
In one aspect, the present invention is a control system for a system for applying fluid onto a drum of a compacting vehicle. The fluid applying system or xe2x80x9cwettingxe2x80x9d system includes a fluid supply and a fluid delivery line having an inlet fluidly connected with the fluid supply and an outlet located so as to direct fluid onto the drum. The control system basically comprises a regulator configured to adjust a rate of fluid flow through the outlet. A speed sensor is connected with the vehicle and is configured to sense vehicle travel speed. Further, a logic circuit is operatively connected with the speed sensor and with the regulator. The logic circuit is configured to automatically operate the regulator when vehicle speed changes such that the regulator adjusts the flow rate through the outlet to be generally proportional to the sensed vehicle speed.
In another aspect, the present invention is also a control system for the wetting system described above. The control system basically comprises a regulator configured to adjust fluid flow through the outlet and a sensor configured to sense rotation of the drum. A logic circuit is operatively connected with the sensor and with the regulator. The logic circuit is configured to operate the regulator such that fluid flow through the outlet is permitted for either one of a predetermined travel distance or displacement of the drum and a predetermined period of time. Further, the fluid flow through the outlet is alternately interrupted for either one a predetermined period of time and a predetermined travel distance of the drum.
In a further aspect, the present invention is also a control system for the wetting system described above. The control system basically comprises a regulator configured to adjust fluid flow through the outlet and a sensor configured to sense rotation of the drum. A logic circuit is operatively connected with the sensor and with the regulator and is configured to selectively operate the regulator in a first operational mode and alternatively in a second operational mode. In the first operational mode, the regulator maintains a rate of flow through the delivery line outlet to be generally proportional to vehicle speed. In the second operational mode, fluid flow through the outlet is permitted for a predetermined travel distance or displacement of the drum and alternately interrupted for a predetermined period of time.